Guide · updated 2026-10-05

Geohash channels, without the jargon

A geohash is a short code for a rectangle on the map. bitchat uses that code as a room name. People who pick the same code can meet in it over the internet, even when their phones cannot hear each other over Bluetooth.

The code is the room

Geohash was invented to write a location as letters and digits. The longer the string, the smaller the rectangle. A very short code can cover a huge region. A long one can cover a few houses. bitchat does not invent this grid. It borrows the grid so that “people around this part of the city” can be a channel name without anyone typing a street address into the chat.

You are not added to the room because of your SIM card. You join because you chose the code, or because the app offered you the code that matches the precision you picked. Anyone else who chooses it can read the public room. Treat a geohash channel like a noticeboard in a park, not like a locked group of friends.

Length is a privacy setting

Precision is the decision people skip. A neighborhood-length code gathers a local crowd and also says you are inside a smaller box. A region-length code says less about where you stand and gathers a noisier room. There is no length that means “only my friends”. Friends are a different feature: direct messages and favorites. The geohash room is geographic on purpose.

The app uses ephemeral keys per geohash area for this online path, as the Android project describes it. That reduces the chance that one long-lived key follows you from city to city inside those rooms. It does not hide the fact that you joined a public channel whose name is a place.

The globe is not the network

Version 2.0.1 adds an animated globe so you can look at the grid, borders, and cities, and it can do that drawing while the phone is offline. Looking at a code is not the same as entering the room. The room’s messages travel through Nostr relays. No signal means you can browse the map idea and you cannot hear the people in the live channel.

The local mesh is still there for the people beside you. If the internet is down, stay on the mesh channel. Switching to a geohash room at that moment sends your typing into a path that cannot leave the phone.

Location permission, again

Android’s location permission is doing two jobs that are easy to mix up. The system demands it for Bluetooth scanning even when you never open a map. The geohash feature uses location a second way: to suggest the code for the area you are actually in. You can refuse to join a room. You often cannot refuse the scan permission and still expect the offline mesh to see peers.

If you want the mesh and you do not want a suggested city room, use the mesh and ignore the globe. The permission prompt will still appear, because Bluetooth scanning is what triggers it.

Notes you leave behind

The public description of the app includes leaving notes for people who later pass a place. Think of that as a message pinned to a code, not as a tracker planted on a person. The next phone learns the note because it asked for that place, not because you pushed it to their number. Do not put a home address, a one-time code, or a Cashu token in a public note. The rectangle is bigger than your doorway, and the room is not a safe.

Related reading: how Nostr carries these rooms and the feature list.